Thornton played under Zimmer, who is scheduled to interview with the Titans on Thursday.

“I think he is ready,’’ said Thornton, who played for the Titans from 1999-2002, said of Zimmer. “The thing that people said about him is that he is too tough, but I don’t think that is the case. Players respond to tough coaches, and players sometimes want that. The guys respond to him.”

Zimmer just finished his 20th season as an NFL coach and in his sixth with the Bengals as defensive coordinator. The Bengals finished the season ranked third in the NFL in total defense, and were in the top five in rushing (5th), passing (5th) and points allowed (5th).

He interviewed with the Dolphins and Buccaneers two years ago and with the Browns last year.

Prior to joining the Bengals in 2008, he served as defensive coordinator with the Cowboys (2000-06) and Falcons (2007).

Along with the Titans, Zimmer is also considered a candidate in Minnesota, Washington, Cleveland and Detroit.

“I think he is definitely ready to be a head coach,’’ Thornton said. “His units have been at the top of the league even when he’s had injuries. He is ready to lead a team and probably put a good staff together as well.”

Prior to current position: Spent his first 15 seasons coaching in the college ranks, starting at Missouri and eventually becoming defensive coordinator at Washington State from 1989-93. He entered the NFL as Cowboys defensive backs coach in 1994 and was coordinator from 2000-06. He spent one year as Falcons defensive coordinator before joining Bengals in 2007.

Pros: If the vocal, intense ways of senior assistant/defense Gregg Williams served as a boost for the Titans in 2012, then Zimmer would be a good fit. … His defense finished in the top 10 in three straight seasons and four of his six as coordinator. … This year it was third in overall (fifth vs. run, fifth vs. pass) despite losing Pro Bowl DT Geno Atkins to a torn ACL halfway through the season. … Bengals finished seventh in sacks with 46, seven more than the Titans posted. … Zimmer played LB in college and has experience coaching them. He helped Vontaze Burfict – who was bypassed in the 2012 draft – turn into a Pro Bowl player who led the league in tackles. … Reportedly has a no-nonsense manner that players respond to.

Cons: Strengths are obviously on the defensive side of the ball, which, it could be argued, needs less immediate help than the Titans’ offense. … He’ll be 58 by the time next season starts, but he’s still received plenty of interview requests over the past couple of years. … Reportedly rubs some people the wrong way with his blunt manner, which may not serve him particularly well as a head coach.

Comment: “One of the best defensive coordinators in the game who has the adoration of his players. Can be blunt at times but if you are looking for a disciplinarian, he is your guy,” — Joe Reedy, Bengals beat writer, Cincinnati Enquirer

Zimmer is in his 20th season as an NFL coach and in his sixth with the Bengals as defensive coordinator. The Bengals finished the season ranked third in the NFL in total defense, and were in the top five in rushing (5th), passing (5th) and points allowed (5th).

He’s expected to interview with the Titans this week.

He interviewed with the Dolphins and Bucs two years ago and with the Browns last year. According to ESPN’s Adam Schefter, the Vikings are also interested in interviewing Zimmer.

Zimmer has a good reputation around the NFL. Prior to joining the Bengals in 2008, he was defensive coordinator with the Cowboys (2000-06) and Falcons (2007).